Working with XShape

Hello.

I hope Tim Robert's right and I got some good responses about this 
besides the bashing :)
I'm working on an application which needs to use XShape extension to 
create a window with a transparent background. So far so good, the 
problem is that this mask has to be changed constantly, using the window 
background as key to it.
Right now what I'm doing, is for every bitmap I need to put on the 
window, I scan for the background color, create the mask, put the image 
and apply the mask using XShapeCombineShape.
Should be straightforward I think, but I'm getting all sort of weird 
things like the mask not doing any effect, etc.
I experimented on creating a fix mask and apply. This works very well, 
the problem seens to arise when I try to manipulate the bitmap mask and 
use it several times.
The documentation I found do far is very thin specialy on examples how 
to use other XShape related functions like XShapeOffsetShape, 
XShapeCombineMask, etc. I took a look in programs that uses it like 
oclock, xteddy, etc but they don't go deep on it.
Does anyone knows a better source of documentation about XShape and it's 
related fuctions in general.
Perhaps I'm messing with the bitmap mask but all the tests I made so far 
indicates that it's been created correctly.
Any advice will be very apreciated.

[]s and thanks.

Adilson.

-- 
Nullum magnum ingenium sine mixtura dementiae fuit - Seneca